1. Field of the Invention
The present invention relates to a signal processing apparatus, a signal processing method, a program, and a recording medium. More particularly, the present invention relates to a signal processing apparatus, for example, which is capable of detecting the position of noise having a specific pattern, generated as a result of YC separation, from a signal after being subjected to a YC separation process, to a signal processing method therefor, to a program therefor, and to a recording medium therefor.
2. Description of the Related Art
In the composite video system, a color video signal in which a Y signal, which is a luminance signal, and a C signal, which is a color signal, are combined is used to improve transmission efficiency. Extraction of the luminance signal Y and the color signal C from the combined signal of the Y signal and the C signal (so-called composite signal) is called YC separation (or luminance/color-difference separation). The composite signal can be transmitted using one cable. With respect to a composite signal, a technology for performing inter-frame YC separation on a still portion of a video signal and for performing intra-field (between lines) YC separation on a moving image portion is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 10-322718.
However, in the current signal processing technology, it is not possible to completely separate the Y signal and the C signal once they are combined. As a result, noise, called dot interference or cross color, due to the fact that YC separation is not perfect, occurs in a signal on which YC separation is performed. In the conventional YC separation technology, it is not possible to completely eliminate this noise due to detection errors, intra-field YC separation errors, etc., in the still portion and the moving portion.
Dot interference refers to a phenomenon in which black dots which do not exist in the original signal occur in the reproduced image (in most cases, these occur in an arranged manner in the horizontal direction). The dot interference is noise which is likely to occur in edge portions where the color changes.
In this manner, when image processing is performed using a signal containing noise after the YC separation processing, there is a risk that, for example, as a result of the noise portion being enhanced further by enhancement processing, or as a result of performing an enlarging process on an image in which noise has occurred, an image having conspicuous noise portions is generated. Furthermore, when a filtering process is performed at the same time as YC separation processing in order to reduce the influence of noise, there is a risk that the resolution of the portion where no noise occurs will be reduced.